1. Field of the Invention
The present invention relates to a magnetic recording device and a magnetic recording method.
2. Description of Related Art
Recently, with increasing surface recording density of a magnetic recording medium (hereinafter, referred to as a “recording medium”) typified by a hard disk, performance improvement of a magnetic write head is demanded. Accordingly, as a recording method with the magnetic write head, a vertical magnetic recording method in which a direction of signal magnetic field is set in a direction intersecting with a plane of a magnetic recording medium is attracted attention, instead of a longitudinal magnetic recording method in which a direction of signal magnetic field is set in an in-plane direction of a recording medium. This is because in the vertical magnetic recording method, linear recording density is increased, and an advantage that a recorded recording medium is hardly affected from thermal fluctuation is obtainable.
A magnetic write head of the vertical magnetic recording method (hereinafter, referred to as a “vertical magnetic write head”) includes a thin film coil for generating magnetic flux, and a main magnetic-pole layer guiding the magnetic flux, which is generated in the thin film coil, to a magnetic recording medium. The main magnetic-pole layer includes a front end portion (a magnetic pole) with a minimal width generating magnetic field for recording (recording magnetic field).
As for the configuration of the vertical magnetic write head, it has been studied that to suppress spread of recording magnetic field and to realize a high-density recording, side shield layers are provided on both sides of a magnetic pole in a direction across write tracks through a gap (for example, refer to Japanese Unexamined Patent Application Publication Nos. 2004-326990, 2004-022004, and 2005-310363).
In recent years, demand on the improvement in surface recording density of the magnetic recording medium tends to increase. Under the circumstances, new magnetic recording method called shingle write method has been proposed (for example, refer to Japanese Unexamined Patent Application Publication Nos. 2006-294162, 2007-73138, and 2010-40113). In the shingle write method, a part of a magnetic write track is overwritten (recording of a subsequent magnetic write track is performed so that some regions of a previously-recorded magnetic write track is overwritten). Accordingly, the width of the magnetic write track eventually obtained may be narrower than the width of a trailing edge of a magnetic pole, and improvement of the surface recording density of the magnetic recording medium is achievable. However, due to such characteristics, except for a final write track, performing data rewriting processing in only an arbitrary unit recording region is physically difficult. Therefore, all magnetic write tracks including magnetic write tracks not essentially requiring rewriting are subjected to recording processing. Accordingly, compared with a typical recording method, processing time taken for data rewriting processing is increased. Therefore, a method in which a plurality of data recording blocks are provided on a magnetic write track, and data rewriting processing is performed for each recording block to reduce processing time for rewriting has been proposed. In this case, the plurality of data recording blocks are arranged so as not to overlap with one another.
Incidentally, in a region at both side ends of the magnetic write track recorded with magnetic data, through which a magnetic pole of the magnetic recording head passes, a erase band (a recording region with an unstable magnetization direction) is generated due to a phenomenon called write exudation. Specifically, when a tilt angle (skew angle) of a main magnetic-pole layer with respect to a tangent direction (a rotation direction of the magnetic disk, or a movement direction of the main magnetic-pole layer) of the write track is large, (although a bevel angle is provided) a relatively large erase band is generated. Therefore, the distance between adjacent write tracks (track pitch) needs to be widened depending on the size of the skew angle so that an effective write track width after recording is a width capable of being read by the magnetic read head. However, when the track pitch is widened, error such as miswriting is avoidable, but the reduction of the surface recording density of the magnetic recording medium inevitably arises.
From such circumstances, a magnetic recording device and a magnetic recording method which have a simple configuration and are capable of responding high-density recording while preventing errors from occurring at information recording processing, are strongly desired.